Well, I've done the first track day in the Coupe and I must say I'm pretty impressed. It needs work to dial out some of the understeer otherwise it did really well, obviously with 300 odd bhp it's going to be fairly quick in a straight line but it didn't put the power down too badly on the bends considering I've got cheepo tyres on. I set the tyres to 3 bar front and 2.5 rear, the n/s/f took a bit of a hammering but Brands is mainly hard right handers so it's to be expected. Anyway a few pics below and as can be seen in these, the n/s/f rolls onto the sidewall a fair bit.

I would like to widen the front track a fair bit but can't bring myself to use spacers so I'm toying with the idea of having some longer driveshafts made (£190 each)and then making up some longer wishbones which will also allow me to dial in as much negative camber as I need. Any thoughts on this?

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay002.jpg

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay006.jpg

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay008.jpg

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay011.jpg

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay024.jpg

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay028.jpg

http://s613.photobucket.com/albums/tt212/MrTscoupe/?action=view&current=TrackDay032.jpg

what is your current suspension / handling setup?

KW V2 and standard roll bars, it's a pretty good setup but with all that weight at the front I think it struggles a bit. I should think that a decent LSD would help a lot as well.

You'll never change the weight up front - I spent a lot of time and money trying. You can get it better though.

What is the ride height, and alignment settings?

LSD is not needed IMO, but you could certainly do with an uprated rear ARB and increasing both camber and caster. Camber could be done with Camber bolts, but to increase the caster you'll need custom top mounts. Corner weighting will also help.

If you:

* uprate the rear ARB (or potentially both the front and rear ARBs)
* increase the front camber to -1deg to -1.5deg (with camber bolts)
* replace the rear subframe bushes with solid ones
* put on front strut braces (upper and lower)

then you'll have a pretty sorted car with understeer minimised pretty well

Cheers guys, that sounds a lot easier as well. The reason I was thinking about increasing the track was because I did this on a BMW 2002 track car I built that I'd put a 535i lump in which was a lot heavier than the original 4 pot. I widened the track by 40mm each side and this absolutely transformed the cars handling, the weight transfer to the out side wheel on hard cornering had been reduced by nearly 100 kilos, althought it was a lot easier to do on a rwd vehicle!

That, and lower springs, adjustable shocks and battery at the rear will make your understeer pretty much go away. (People always question me about moving a heavy lump like the battery, but The Fact is I did it and I felt the difference)

Dunno about 40mm extra track in the long run, your wheel bearings will suffer. But if you can afford that, sure!

Lowering the car does not help much - if at all!

I never tried putting the battery in the boot, so I'm not sure what difference that would make. However taking out the spare wheel does make a difference to the rear 'lift' when on the brakes.

The biggest difference you will notice without spending a lot of money is the tracking - I found half a degree of toe out on the front really helps getting power down out of bends, which in turn helps stop understeer.

Putting the battery in the boot is probably ok in a LHD coupe but on a RHD car it's not going to do you many favours, the coupe is already heavy at the RH side, add a driver and then remove the battery from the LH side is only going to make that worse

I guess he must be using rain-x with an empty washer bottle and carrying a passenger

put the battery on the left hand side of the boot:)

well here we go again.. old joke matey..

If you're keeping you Coupe strictly std - fair, but this mod is as worthy as any of those more/less silly braces etc.
I felt less difference before/after the Sparco strutbrace. Soak it in..


Yeah was just about to say it.

You're never really get rid of the understeer. the coupe has tons of mechanical grip though. adjust your lines a bit to take advantage of what the coupe has - boatloads of torque and power - and you should still do good laptimes.

im competitive with similarly powered RWD silvias and 4WD evos cos i know my lines.

redd

And check your tyre pressures. They can mean a LOAD of difference with the Coupe. After a warmup lap I used to set them up 2.0 to 2.2 bar at the front and a bit higher (2.4 - 2.5) at the rear to loosen it up a bit there with the standard P Zero's. If you change something, be prepared for some test laps to try it all out. Even different brand tyres can affect handling.

sorry if its off topic but can you you do a how to guide on locating the battery to the boot please!

I am just about to do this on mine Marco, not necessarily to move weight around but to make a bit more room under there! I'm also taking the aircon off for the same reason. I've already run the cable through so I'll do a few pictures when I do the rest.

There's been lots of different ideas and comments on this understeer thread, all valid but don't get me wrong the coupe was still very quick, I should have some video to post soon.

Yes I suppose I can, did one on the old forum but that's long gone..

it maybe around in the archives?

Here they are:

Pers guide in swedish?
http://sfk.ibk.se/forum/showthread.php?s=155c496e925ff5d405dce05d114157b1&threadid=5311

Some debate on it:
Discussion

More

Some more

As mentioned in the thread, two updates on my guide:

# there are better routes for the pluscable thru the bulkhead, namely behind the left wing.
# thicker plus cable
# use gelbattery's (I now use twin 18Ah gel's) which will reduce acid stains on the boot paint..

hmm, having a little trouble translating Pers guide in Swedish...

any help?

Understeer - Fronts are probably too stiff and you need more stiffness in the rear. Also with the coupe being a heavy front engined car understeer will always be a problem. I feel you have to drive the car accordingly whih means be a bit more firm with turn in which in turn will get the rear moving and help you at the same time. You can spend fortunes trying to alleviate it when you might only need to alter how you drive it. Remember you are on track which is smooth and grippy tarmac, not the road so don't be shy and get the chassis working for you don't wait until it tells you what it wants to do.

and thats exactley what i saw you doing to yours Marco at time attack!

Just got the video through which shows a fair bit of body roll and my nephew who was following me and filming said that the rear end looked very "twitchy" which perhaps confirms that it was the back end that was letting it down.

What rear ARB and solid mounts are recommended?

Whiteline or eibach 22/24mm ARBs.

Solid mounts are custom made jobbies only I'm affraid. There was a group buy for them, plus I think that dink can also get hold of some.

Chris

That's great, thanks Chris.

The ones from the GB are based on my design nobby In fact it was me who provided the drawings to MatB way back in 2007 who in turn passed them on to 13ad13oy who launched the GB

then again sederich was the first one to have them on the car i guess.

Further to the understeer problem i like to get the car as neutral as possible towards oversteer.

Here's my recipe:


rear axle (requires the biggest amount of work) :
- 22mm anti-roll bar reduces understeer the rear becomes more stable and better fell with the car. One of the best mods i'd say
- Stiffer springs will further reduce understeer and also a bit less roll
- Solid bushes are recommended if your bushes are worn, new OEM bushes are pretty ok too.
.

Front :
- Keep the stock roll bar you will get less understeer, only for race cars i'd recommend a bigger font roll bar.
- -1 to -1,5 degrees of camber for a road car
- like mentioned 0,5mm of toe out seems to work well
- Powerflex bushes: ok here's the snag, it will steer a lot better and put the power down with the bushes on but in theory they aid understeer. A necessary evil i'd say.

braking :
- Adjust the brake proportioning valve to increase the braking on the rears.

Finally: tracking, tracking, tracking... Good tires...

Indeed you did. And I'll take the opportunity to say thank you once again.

Don't forget the front lower brace (here's mine: mine 1 and
mine 2.)

It's not reducing understeer much, BUT with negative camber + toe-out you WILL get much more torquesteer. This reduces torquesteer heavily.